Conventional outdoor or streetlight housing assemblies typically use aluminum-based reflective coatings. Unfortunately aluminum-based reflective coatings have several drawbacks. Firstly, the theoretical reflectance of these coatings in the visible spectrum is about 91%, however the reflectance of an aluminum film with a typical topcoat produced from a coating process is only about 80%. This level of reflectivity is not the highest among available materials.
Secondly, aluminum has poor adhesion to plastic fixtures or basecoats. Polymer basecoats are often required in outdoor lighting assemblies in order to smooth out surfaces and for minimizing roughness and scratches. In conventional outdoor lighting assemblies, a ultra-violet (UV) cured polyimide is applied evenly to the surface of the lighting assembly and a thin film of aluminum is adhesively placed on top of the base coat to create an aluminum/base coat film system. Unfortunately, moisture in air attacks the aluminum/base coat film system, especially in high temperature and high humidity environments. As a result, the aluminum thin film coating deteriorates, and can easily peel off. Therefore, this is not an ideal material for long-term use in an outdoor environment.
It is more desirable to have a highly reflective material (95-100% reflective) that does not have the failings of the aluminum/base coast film system. It is also desirable to have a highly reflective coating that can tolerate the rigors of an outdoor environment. Furthermore, it is desirable to have a reflective material that is offers higher reflective lumens in the visible spectrum when paired with an LED array. Furthermore, it is desirable to have a reflective material this suitable for both indoor and outdoor use with LED arrays.